SE447509B - PULSATE BALANCED CONTROL LOOP DETERMINED FOR SPEED HOLDING IN A DRY TUNED DOUBLE SHAFT GYRO - Google Patents

Description

Accordingly, an object of the invention is to provide a pulse width modulated holding loop for a gyro with two-degree freedom.

Preferred Embodiments The above and other objects, features and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, in which: Fig. 1 is a block diagram of the pulse rebalanced velocity loop circuit for a two-axis dry tuned gyro according to the invention, Fig. 2 shows graphs of the time relationships between pulse width modulated and quantized waveforms, Fig. 3A shows a detailed block diagram of the logic block 30 of Fig. 1 and Fig. 3B graphically shows the logic signals.

Fig. 1 shows a block diagram of a pulse rebalanced speed-holding loop circuit for a two-axis dry-axis tuned gyro according to the invention. Each velocity component I along either the X or Y input axes of gyros 10 generates a gyro torque around their sensor axes, causing the gyros 10 wheels to adjust. The gyro sensors 13, 14 sense the wheel position and provide a proportional electrical signal to AC amplifiers 16, 17. From the amplifiers 16, 17 the signal is transmitted via demodulators 18, 19, chopping filters 20, 21 and attenuation compensating cross channel circuits 24, 25. The outputs from those in The shaping circuits 22, 23 located in the main channels are summed in comparators 27, 28 with both the output signals from the cross channel circuits and a signal from a ramp generator 26. The ramp generator signal is required to generate a pulse width modulated signal, the fundamental frequency of which is the frequency forced the border cycle. The forming circuits 22, 23 of the main channels provide for loop stabilization and bandwidth control. The purpose of the attenuation compensating cross channel circuits 24, 25 is, as the name implies, to provide electronic attenuation, which is new for a dry tuned gyro. 10 15 20 25 30 35 447 509 3 The chopping filters 20, 21 are required to keep any sensed signal induced by the movement of the wheel to a minimum.

The variable pulse width modulated signals obtained from the summation of both the ramp generator signal and the output signals from the main and cross channel circuits are fed via logic circuits 29, 30, which control the switching from positive to negative torque current. This switching is designed to take place synchronously with a high-frequency pulse train. As a result, each part of the pulse width modulated signal receives an integer number of high frequency clock pulses. For example, at a 50% intermittent factor, each positive and negative half of the pulse width modulated signal contains an equal number of data pulses.

Pig. 2 shows the time relationships between the pulse width modulated signal and the quantization waveforms. The ramp generator signal has a zero average value and a frequency equal to the frequency of the imposed limit cycle.

This signal, which is negative at first, but becomes positive at half the period, is summed with the combined error signal from the outputs of both the main and cross channel circuits in summing amplifiers 27, 28. The output signals from the summing amplifiers are fed to comparator circuits in blocks 29, 30, which switches from a logic "0" to a logic "1" when the buzzer of the summing amplifier changes from negative to positive value. For a zero error signal, the comparator output signal switches the logic value at a point midway between the ramp periods (at which point the ramp passes through zero) to generate a 50% intermittent signal. For non-zero signals, the comparator output is a logic signal with an intermittence proportional to the error.

From Fig. 3 it can be seen that the comparator output signal is gated with a high frequency clock signal in the gate 33 of the timing circuit 30 (Fig. 1) to generate a binary signal with the frequency of the ramp generator signal and with very dense control of the switching points. This signal is sent to a strobe circuit (not shown), which generates readout signals on two different data conductors (the difference in pulse current on the two conductors is proportional to the input signal speed), and to a 447 509 10 15 20 H control flip-flop 36. The output flip-flop 36 goes to two fast transistor switches 37, 38 (shown here as mechanical switches for simplicity). These switches connect either the positive + V source or the negative -V source to the output power source in accordance with the position of the control flip-flop 36 according to Fig. 3B. The output current sources 31, 32 according to Fig. 1 are very accurate high-speed sources, which feed directly on the gyro torque sensors 11, 12 according to Fig. 1 and have one end grounded. The current sources 31, 32 are not in themselves grounded but flow between the positive and negative direct current sources and the gyro torque sensor. The current flows continuously in the current sources and always in the same direction, the current direction in the torque sensor being controlled by means of two commutation diodes CR1, CR2 and the two quick switches 37, 38.

The current through the torque sensor is thus constant in size (which means constant power in the torque sensor), its pulse width modulated binary format and has a repetition rate equal to the ramp frequency. Although particular embodiments of the invention have been described in connection with the drawings, it will be apparent to those skilled in the art that various modifications may be made without departing from the spirit of the invention, which is limited only by the appended claims.

Claims (3)

10 15 20 25 30 447 509 PATENT REQUIREMENTS A pulse rebalanced control loop intended for speed maintenance in a dry tuned dual shaft gyro (10) and comprising means (13, 1 &) for sensing the gyros electrically by means of electrotorator position means and emitting a correspondingly proportional error signal, capable of attenuating the error signal and comprising comparators (27, 28) fed with error signals from both axes of the gyros (10) and having an input connected to the output of a cyclic ramp generator (26), the output signals obtained from the comparators (27, 28) via means (29, 30) being arranged in response to the electronically attenuated signal or alternatively feed gyros with a positive or negative torque current to reduce the error signal. 2. A control loop according to claim 1, characterized by a pair of main channels (16, 18, 20, 30 and 17, 19, 21, 29, respectively) with one AC amplifier (16, 17) for amplifying the error signal from the sensor means ( 13, 1 &) arranged in each main channel and to supply demodulators (18, 19), each of which emits a processed signal via a filter circuit (20, 21), partly a shaping circuit (22, 23) in each main channel and partly a cross channel circuit (24, 25) for exchanging error signals from the two sensor means (13, 14), the comparators (27, 28) being connected to be supplied with the output signals of the main channel and the cross channel circuit and with the ramp voltage signal obtained from the ramp generator (26). Control loop according to claim 2, characterized by logic means (29, 30) for alternatively feeding gyros (10) with the positive or negative torque current and of constant current sources (31, in response to the output signal of the comparators (27, 28). 32) in order to produce a pulse-modulated torque current in response to the logic means.